After bladder TURB, there are five major imaging findings which can be confounding:

1. Partial or total absence of the bladder wall in the site of the prior TURB (figures 3 and 4): due to the excision of a part of the bladder wall, the wall defect itself can be visible in all sequences. Tends to persist in time, but it does not pose such a big diagnostic dillema, as there is frequently no remaining lesion or signal intensity change related to the wall thinning.
2. Bladder wall thickening and/or wall retraction following TURB (figure 5): it is mostly due to inflammatory changes at first, and secondary to scarring and fibrosis after some time. To our experience, this is one of the most frequent finding after TURB, sometimes lasting for months. The scarring and inflammation might happen in a larger area compared to the TURB bed, but is almost always surrounding the TURB site. The sole wall thickening and retraction in the morphologic sequences (mainly T2 weighted images) is not so suspicious, but when it is accompanied by changes in the following functional sequences (DWI and DCE), it is a major challenge.
3. Perivesical fat edema and/or stranding (figure 6): this is, to our experience, one of the least lasting postTURB changes. It is secondary to a deep TURB sampling, which can sometimes affect the full thickness of the muscle layer and even the adventitia, therefore provoking a small traumatism to the perivesical fat. If associated with wall thickening and other imaging changes, it poses a differential diagnosis with transmural invasive lesion (VIRADS 5 lesion).
4. Mild vesical wall edema in the intervened area that is represented by a mild diffusion restriction (figure 7): it is not a frequent change observed after TURB. The thickenned and inflammed or edematous wall can have a mild diffusion restriction, with lower signal intensity in the high b value sequence and higher signal intensity in the ADC sequence compared to the resected lesion or the truly remaining tumor. Probably the most challenging postTURB MRI finding, as sometimes the difference in the grade of diffusion restriction is very subtle.
5. Early and avid enhancement after contrast administration in the bladder surface (figure 7): following TURB, and lasting for more than 6 to 8 weeks after the procedure, the inflammed mucosa and superficial layer of the bladder will enhance strongly in the early postcontrast sequences. It is another very frequent finding, which is a diagnostic dilemma when associated with the previously described cases.

Most of the cases from our centers were given VIRADS 3 or 4, while most of the lesions, after a new TURB or surgery, were proven to be NMBIC. This goes along with the published data, which shows that, even if the sensitivity is high, the specificity, PPV and NPV of current VIRADS classification is very low when applied in postTURB studies, even if they were performed more than 6 to 8 weeks after the TURB.

We hereby present some cases (figures 4, 6 and 8-12) of patients with bladder MRI after TURB, with various chronologies. In some cases, the bladder MRI was performed to rule out muscle-invasive tumour remnants. In those cases, the given VIRADS score is annotated, and the final pathology report is offered afterwards for comparison.